A Jon boat has a lot of advantages. The flat bottom takes less power to plane and also makes is much more stable in the water for when you're fighting a fish near the gunwales or entering/exiting from a dock. The downside is a punishing ride if things get bumpy on the water. Having said that, a lightweight vee isn't that much better. Where a vee really shines on choppy water is when it has some heft to it, or you can shift some weight forward to get the vee to cut instead of ride on top. Truth be told, many of the aluminum vees you'll find are only a vee in the very front and taper to a mostly-flat bottom at the back.
Another Jon boat advantage is that it tends to be slightly less picky about where the weight is in the boat. I have a 12' vee and a 14' vee, both with a 9.9. With my fat butt in the back and the motor trimmed fully down, they both still bounce (porpoising) if I'm alone in it, and a good gust of wind sends the bow in another direction.
Yet another Jon boat advantage is that the floor inside is flat. You can stand 6" from the gunwales. In a vee, you can't really do that unless you construct a floating flat floor in it... which further amplifies how much the boat rocks when you shift your weight.
A small vee is a sit-down boat. You can stand up, but you're standing on a crooked floor and it's less stable.
Another downside to a Jon boat is that they tend to be a bit heavier than a same-length vee, but not by much.
Brands I like: Lowe, Alumacraft, Tracker, SeaArk, Crestliner, Princecraft, Lund, SmokerCraft. There really isn't much to screw up on a small aluminum craft, so it's not like other brands are "bad," but those are plentiful, quality, and should be easy to find.
Another thought... if you're handy at tinkering, don't shy away from a bargain if it has an old motor. Old 2-strokes tend to be bulletproof. I currently have in my arsenal two 30hp Evinrudes from the early 80s, a couple 9.9 Johnsons from the 90s, an 88 Mercury 70hp, a 20hp Johnson from 76, an Evinrude 6hp from 1968, and an Evinrude 10hp from (gasp) 1961, and they all get used. I mean USED for three months a year several times a day. I estimate that the Mercury 70 is well over 10,000 hours. Just keep in mind an important thing... Before 1981, all hp ratings on outboards were rated at the flywheel. 81-84, they started rating some outboards at the prop. By 1985, the BIA required them all to be rated at the prop, so a 1975 20-hp motor is actually putting about 15-17 hp to the prop, while a later 20hp motor is actually putting 20 to the blades.
Can you tell us more about the water you'll be on? How far is it to the fishing spots? River or lake? Restrictions on hp? The reason I ask is because if you'll be on a 1-mile lake, you could get away with a 2hp motor and putter along, but if you're on a river with a current, it might be more appropriate to... you know, go faster than the current? :)